Annual Calendar Month Transition Corrector
Map a Gregorian month-end through a conventional annual-calendar model that handles 30-day months and treats February as 30 days.
Description
An annual-calendar model handles 30- and 31-day months but treats February as 30 days.
An annual-calendar model handles 30- and 31-day months but treats February as 30 days. Gregorian February therefore needs manual correction at month end.1
Map a Gregorian month-end through a conventional annual-calendar model that handles 30-day months and treats February as 30 days.
When to use Annual Calendar Month Transition Corrector
Use this tool to map a Gregorian month-end through a conventional annual-calendar model that handles 30-day months and treats February as 30 days.
Choose a supported reference focus or prepare the watch measurements, evidence and explicit limits requested. Confirm units and date conventions before running.
How to use Annual Calendar Month Transition Corrector and understand its results
- Choose a supported reference focus or prepare the watch measurements, evidence and explicit limits requested. Confirm units and date conventions before running.
- Enter day, month, year using the field table and calculation rules, then run the tool.
- Read correctionRequired, modeledMonthLength, nextCalendarDate, nextMonth, nextYear, transitionReason. The explanation below defines the units, signs, ordering and any flags or placeholder values.
- If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.
| Input field | Meaning | Value type; see rules below | Requirement |
|---|---|---|---|
| day | Gregorian day | integer; minimum: 1; maximum: 31 | Required |
| month | Gregorian month | integer; minimum: 1; maximum: 12 | Required |
| year | Gregorian year | integer; minimum: 1; maximum: 9999 | Required |
Enter valid Gregorian integer year 1–9999, month and day. Return modeled month length, correction flag, next date/month/year and explanation. Leap-year February requires one skipped date; ordinary February requires two.
correction=last actual February day; nextDate=ordinary Gregorian next day Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| correctionRequired | Manual correction indicated | boolean |
| modeledMonthLength | Modeled month length | integer; minimum: 28; maximum: 31 |
| nextCalendarDate | Next Gregorian date | string |
| nextMonth | Next month | integer; minimum: 1; maximum: 12 |
| nextYear | Next year | integer; minimum: 1; maximum: 10000 |
| transitionReason | Transition reason | string |
{
"input": {
"day": 29,
"month": 2,
"year": 2024
},
"output": {
"correctionRequired": true,
"modeledMonthLength": 30,
"nextCalendarDate": "2024-03-01",
"nextMonth": 3,
"nextYear": 2024,
"transitionReason": "The annual-calendar model inserts one or two non-existent dates after the Gregorian end of February, so manual correction is required."
}
}Limitations and assumptions
No actual watch calendar is advanced. Advancing 9999-12-31 returns nextYear 10000 and date 10000-01-01, beyond the accepted input-year range.
Numeric inputs, where present, must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors. A successfully returned false flag is an evaluated outcome; its meaning is explained above.
Alternative or Complementary methods
Use Gregorian Leap Year Cycle Calculator: Apply the Gregorian leap-year rule to a year, including century exceptions and the distance to the next leap year. For a complementary task, use IANA Zone Offset at Instant: Resolve an IANA time-zone identifier to its UTC offset and local date-time at an explicit UTC instant, including daylight-saving changes in the runtime time-zone database.
References
Similar or alternative tools
- Gregorian Leap Year Cycle Calculator
Apply the Gregorian leap-year rule to a year, including century exceptions and the distance to the next leap year.
- IANA Zone Offset at Instant
Resolve an IANA time-zone identifier to its UTC offset and local date-time at an explicit UTC instant, including daylight-saving changes in the runtime time-zone database.